Engineering News

Organic Solar Cells Regenerate by Emulating Plant Leaves

Scientists have created a solar cell with a structure that mimics the vascular system of plant leaves, making it capable of independent regeneration after incurring damage from exposure to the sun’s ultraviolet rays.

The device, developed by scientists at North Carolina State university, is a form of dye-sensitized solar cell (DSSC) and makes use of light-sensitive organic dye molecules to generate electricity following excitation by the rays of the sun.

While DSSCs have the potential to become a cheaper and more environmentally friendly alternative to the silicon-based solar cells which currently dominate the photovoltaics sector, their chief disadvantage is the susceptibility of their organic dye molecules to degradation following exposure to the sun’s rays – a fatal flaw for a device which harvests the sun’s radiation for energy.

The regenerative solar cells developed by Orlin Velev and Hyung-Jun Koo of NC State solve this dilemma by making use of microfluidic channels to pump fresh dye molecules to those parts of the device which have suffered degradation while simultaneously flushing out the exhausted dye, thus restoring the device’s functionality.

These microfluidic channels emulate the structure of the vascular systems in plant leaves, enabling the fresh dye to be channeled to those areas in need of repair with the greatest amount of efficiency.

According to the developers, this process enables the solar power cells to retain their effectiveness over multiple cycles of replenishment.

“Organic material in DSSCs tends to degrade, so we looked to nature to solve the problem,” Velev said in a statement. “We considered how the branch network in a leaf maintains water and nutrient levels throughout the leaf. Our microchannel solar cell design works in a similar way.”

Velev, who is a professor of Chemical and Biomolecular Engineering at NC State and the lead author of a paper on the new device published in Scientific Reports, says testing of the microchannel networks based on vascular structures in nature has proven it to be far more effective than existing gel-microfluidic cell designs.